A window film is commonly used on a building window or a vehicle window. An earlier window film is prepared using a coating process and is called as sun paper or tea paper, this window film plays a main role in shading strong sunlight, and does not have a heat insulation effect basically.
Based on the researches, a window film prepared by a process of adding a heat absorbent in a deep dyeing way can absorb infrared rays in sunlight so as to achieve a heat insulation effect. However, this window film absorbs visible light at the same time of absorbing the infrared rays, thereby causing insufficient transmittance of the visible light and poorer definition. In addition, the heat insulation function of this window film quickly attenuate, and this window film is more likely to fade.
In order to improve the heat insulation of the foregoing window film, people prepare a window film using a vacuum heat evaporation process. The vacuum heat evaporation process refers to evaporating an aluminum layer on a base material so as to achieve a heat insulation effect. The window film prepared using this method has persistent heat insulation. However, the clarity of this window film is lower, the vision comfort is affected, and the light reflection is higher.
In order to improve the clarity and reduce the reactivity, a window film is prepared using a metal magnetron-sputtering process currently. The metal magnetron-sputtering process refers to: uniformly sputtering metal particles of materials such as nickel, silver, titanium and gold to a high-tension Polyethylene Terephthalate (PET) base material at high speed with high strength under the interaction of an electric field and a magnetic field using a multi-cavity high-speed rotating device. The window film prepared using the magnetron-sputtering process has, higher clarity and low reflective characteristics, in addition to better metallicity and stable heat insulation performance.
Chinese Patent Application No. 201110403335.4 discloses low-radiation coating glass and a manufacturing method thereof. The coating includes a plurality of dielectric combination layers and AZO (Aluminum-doped Zinc Oxide) medium unit layers disposed between the adjacent dielectric combination layers; the AZO medium unit layer includes a functional layer and AZO medium barrier layers, the AZO medium barrier layers lay on two sides of the functional layer. The low-radiation coating provided in the conventional art has the advantages of high transmittance and low reflection of visible light and low transmittance and high reflection of infrared light. However, this low-radiation film is poorer in adherence, a vehicle window is glass having a certain curved surface, the curved glass cannot be directly coated with a coating, the surface of a flexible base material is coated with a coating firstly, and then the flexible base material is adhered to the vehicle window glass. Since this low-radiation coating is poorer in adherence and is more likely to peel off from the flexible base material, application of this low-radiation coating to the field of window films is restricted.